This week’s pearls is a series on “Name that Poisonous Beast!”.  So, let’s start.

Name this poisonous beast:

A)

brown-recluse-300x197

And its 8-legged colleague:

B)

black-widow

  • A) Brown Recluse spider (Loxosceles): cytotoxic, hemolytic venom
    • Initially unnoticed bite
    • Within hours: painful, local erythema
    • 6 hours: hemorrhagic blister, blanching
    • 2-4 days: ecchymotic, necrotic, local tissue loss
    • Less frequent – systemic findings: malaise, nausea/vomiting, fever, myalgias
      • Rare complications: hemolysis, coagulopathy, renal failure, death
    • Treatment: dapsone (questionable efficacy, only in first 48 hours, ensure no G6PD deficiency), antihistamines, steroids, topical nitroglycerin, hyperbaric oxygen (wound care)
    • Antivenom not available in US; only in South America (more dangerous species), though definite benefit not established
  • B)  Black widow spider (Latrodectus): excitatory neurotoxin venom (via exocytosis of NTs)
    • Initially minimal pain
    • Target lesion (blanched circular patch w/surrounding red perimeter and central punctum)
    • 1 hour – systemic symptoms, including:
      • Muscle cramping, nausea/vomiting, headache, anxiety
      • Hypertension, tachycardia, tachypnea, diaphoresis
      • Abdominal rigidity
      • Weakness, fasciculations, paraesthesias, ptosis, lacrodectus facies [facial spasm, eyelid edema, lacrimation]
      • Rare: pulmonary edema, CV collapse, cardiomyopathy, ileus, priapism, hematuria, Horner syndrome, compartment syndrome, rhabdomyolysis, TEN, death
    • Treatment: local wound care, analgesia, muscle relaxants (benzodiazepines, methocarbamol, unclear efficacy), antiemetics
      • Antivenom only for severe cases (poses high risk for allergy, serum sickness)
      • Do not give IV calcium for muscle pain/spasms